1. Field of the Invention
The present invention relates to an apparatus for measuring a trajectory of a flying ball.
2. Description of the Related Art
A golf ball flies by hitting with a golf club. If the trajectory of the golf ball is measured, it is useful for the performance evaluation of the golf ball, the performance evaluation of a golf club and the diagnosis of a swing form of a golf player.
Japanese Laid-Open Patent Publication No. 6-323852 has disclosed a measuring apparatus using a CCD camera having a shutter function. In this apparatus, image data photographed by the CCD camera are taken into a calculating portion and a change between image frames is written to a multilayer memory by an image processing. The trajectory of the golf ball is measured from a multilayered image thus obtained. In the measuring apparatus, the trajectory of the golf ball can be observed but time series data on the position coordinates of the golf ball cannot be measured.
Japanese Laid-Open Patent Publication No. 2001-145718 has disclosed an apparatus for measuring the trajectory of a golf ball based on image data obtained by a CCD camera provided behind a launch point and image data obtained by a CCD camera provided on the side of the trajectory (a perpendicular direction to a flight direction). In this apparatus, a large number of CCD cameras are to be provided on the side. In addition, in order to measure the trajectory by the apparatus with high precision, it is necessary to sufficiently increase a distance between the CCD camera provided on the side and the golf ball. In a general golf course or a testing field for a golf article manufacturer, a distance in a hitting direction is long and a side space is small. There are many restrictions on the installation of the apparatus.
Japanese Laid-Open Patent Publication No. 2003-42716 has disclosed an apparatus comprising a CCD camera for photographing a flying ball from behind and a CCD camera for photographing the ball from ahead and serving to calculate the coordinates of the ball by the calculus of finite differences based on images obtained by these cameras. In the calculus of finite differences, a difference peak hold processing is carried out in order of frames for image data obtained by the CCD camera. More specifically, a pixel memory having a great change from a previous frame is held in a certain frame. Since a flying ball moves within an angle of view, the difference peak hold processing can be carried out.
If the direction of the movement of the ball is coincident with the direction of the optical axis of the camera in the calculus of finite differences, the position of the ball in a certain frame is coincident with the position of the ball in a next frame. In this case, the difference peak hold processing cannot be carried out. In the measuring method, a part of a trajectory is not measured in some cases.
It is an object of the present invention to provide an apparatus capable of measuring time series data on the position coordinates of a flying ball with high precision.